In a wireless cellular communication system, an Evolved Node B (eNB) or Base Station (BS) is a device providing wireless access for User Equipment (UE) which may also be called a terminal, and the eNB or BS performs wireless communication with the UE through an electromagnetic wave. One eNB or BS may provide one or more serving cells, and a wireless communication system may provide wireless coverage for terminals within a certain geographical range through the serving cells.
In order to provide wireless communication for users in a large range, a wireless communication system is required to deploy an eNB or BS with a large coverage area, such an eNB or BS is usually called a macro eNB or macro BS, and its serving cell is usually called a macro cell. In addition, in consideration of different requirements of users and different application environments, the wireless communication system is required to provide users with wireless communication service for compensating coverage holes or provide users with wireless communication service having higher quality, so that some small eNBs or BSs with narrow coverage ranges and lower transmitted power are adopted. These small eNBs or BSs include pico eNBs or pico BSs and femto eNBs or femto BSs, wherein the femto eNBs or femto BSs may also be called Home NBs (HNBs) or Home eNBs (HeNBs), cells provided by the pico eNBs or pico BSs are called pico cells, and cells provided by the fembo eNBs or femto BSs are called femto cells. Nodes corresponding to small eNBs or BSs are also called Low Power Nodes (LPNs), and cells corresponding to these LPNs are also called small cells. The macro eNBs or BSs, the small eNBs or BSs, the pico eNBs or BSs and the femto eNBs or femto BSs may also be collectively referred to as Transmission Points (TPs).
When an ideal backhaul link connection is adopted between a macro eNB or BS and a pico eNB or BS, or between a pico eNB or BS and a pico eNB or BS or between a macro eNB or BS and a macro eNB or BS, rapid handover between the eNBs or BSs may be implemented. For example, when an ideal-backhaul link connection is adopted between a macro eNB or BS and a pico eNB or BS, the pico eNB or BS may be considered as a “virtual distributed antenna” of the macro eNB or BS, UE accessing the pico eNB or BS may also be considered to access the macro eNB or BS, and it may also be considered that the UE may be rapidly handed over between the macro eNB or BS and pico eNB or BS which adopt the ideal-backhaul link connection.
However, under some circumstances, for example, under limits of an environmental factor or a cost factor, only a non-ideal backhaul link connection may be adopted between eNBs (or BSs), and when UE is handed over between the eNBs (or BSs) adopting the non-ideal backhaul link connection, data transmission between the eNBs may be delayed, which disables the UE to rapidly switch between the eNBs and influences the performance of the UE. Particularly for a scenario with more small cells, the probability of handover between eNBs or BSs adopting a non-ideal backhaul link connection is higher, and the performance of UE is influenced more by incapability of rapid handover.